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DENTAL ENGINE.

No. 480,678. Patented Aug. 9, 1892.

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DENTAL ENGINE.

No. 480,678. Patented Aug. 9, 1892.

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CHARLES IV. THOMAS, OF JERSEY CITY,

NEW JERSEY, ASSIGNOR OF FIVE- SIXTHS TO PHILIP VAN VOLKENBURGH, OF NEW YORK, AND JOHN H. PENDLETON, OF BROOKLYN, NEW YORK.

SPECIFICATION forming part of Letters Patent N 0. 480,678, dated August 9, 1892.

Application filed October 21, 1890. Serial No. 368,855.

(No model.)

To all whom it may concern.-

Be it known that I, CHARLES W. THOMAS, a citizen of the United States, residing at J orsey Oity, county of Hudson, in the State of New Jersey, have invented a new and useful Improvement in Dental Engines, of which the following is a specification.

My invention is an improvement in those portable drilling-machines commonly known I0 as dental engines, whose rotative force is derived from an electric motor; and my improvements comprise a means for starting the drill from a state of rest to either a right or left rotation or changing it at will from right to left or left to right through the agency of a special pair of electric magnets in a local circuit which is of much less voltage than that which impels the drill-motor.

In the accompanying drawings, Figures I and II show in side elevation the lower portion and the extreme upper portion of a dental engine embodying my improvements, the friction-wheels and electro-magnets on the near side being omitted. Fig. III is a front,

and Fig. IV a rear, elevation of the parts shown in Fig. I. Fig. V is a section on the line V V, Fig. IV, the starting and reversing circuit being represented diagrammatically. Fig. VI represents a starting and reversing o switch. Fig. VII shows the preferred form of the starting and reversing switch. Fig. VIII shows the operating mechanism when applied to a more simple machine adapted to operate in only one direction.

3 5 1 may represent the base, and 2 the standard, of any suitable supporting frame or pedestal.

3 is an electric motor, and 4 are conductors which connect said motor with a source of electric current. The armature-shaft 3 of said motor, instead of being geared directly to the drill-shaft, is made capable of being brought in connection therewith by means of a peculiarly-arranged friction-clutch of the I following construction,to wit: The armatureshaft carries two wheels 5 5, which may have the represented salient V-formed periphery to mesh as friction-wheels with one or other of two V-grooved wheels 6 6 on countershafts 14 14:, which are journaled on a frame or bearing '7, which rocks on fulcrums 8. These parts are so proportioned that either the wheels 5 and 6 or the wheels 5 and 6 are brought in effective contact, according to whether said frame is rocked to the right or to the left. Suitable transmittingmechanism,

to be presently explained, so connects the wheels 6 6 with the drill-shaft as to rotate the drill forward or backward, according to which wheel is engaged. When not rocked 6o forcibly either to right or left, no motion is transmitted to either wheel, and consequently none to the drill. The wheels 5 6 and 5' 6' I refer to as the friction-gear.

The means for operating the rocking bear- 6 5 ing 7 consists as follows: 9 9 are two electric magnets, of which either magnet is capable of being energized by connection with a voltaic battery or other local source 10 of electric current of small electro-motive force by means of a switch 11. (See Fig. VI.) IVhen this switch is stopped at the intermediate position indicated by dotted lines in Fig. V, both electro-magnets are out out of circuit and are consequently inert. To enable these electromagnets to be brought to bear on the rocking bearing 7, the said bearing is provided with to thus bring the V-grooved wheel 6 (or 6) at that end in effective impact with its frictionwheel 5, (or 5'.) Each -grooved wheel is on a separate transmitting shaft 14 14, and each shaft carries a grooved sheave 15 15', the respective sheaves being connected by belting 16 16 with sheaves 17 17, both fastened to the same shaft 18. One of these beltings 16, being crossed, operates when in motion to drive its sheave 17 in the reverse direction to that given to sheave 17 by the operation of the belting 16. A common sheave 19, being fastened to the same shaft 18, revolves either forward or backward, according to which of and reversing switch is operated, being en tirely distinct from the much more powerful one that operates the motor, the said switch can be manipulated without danger to the user.

The above-described illustration of my in vention may be modified in its minor details. For example, instead of a single starting and reversing switch moving in a tangent to the standards, as shown at 11 in Figs. V and VI, I may employ two normally-open contactsprings 11 11", Fig. VII, of which one or the other may be compressed radially of the standard, according to whether right or left drill rotation is desired. The sheaves 17 17 19 may be of diverse diameters. The local current source and the electro-magnets and electric motor may be protected by any suitable casing and the conductors by inclosure within the tubular portions, (standards 2, flexible shaft 23, 850.)

Iclaim herein as new and of myinvention 1. In a dental engine, the combination of a drill and its supporting-holder, an electric motor for driving the same, connections between the motor and the drill, two independent friction-gears, and independent connections between said friction-gear and a common driving-sheave, whereby the direction of the drill can be altered, substantially as shown and described.

2. In a dental engine, the combination of a drill and its supporting-holder, the normallyopen contact-springs arranged in said holder, an electric motor for operating the drill, a tilting frame and friction-gear 5 6 5' 6 and connections between said friction-gear and the drill, a supplementary battery, and means, substantially as shown and described, under the control of the contact-springs for tilting the gear-carrying frame and stopping, starting, or reversing the direction of the drill, as set forth.

CHAS. W. THOMAS.

Witnesses:

HERBERT KNIGHT, M. V. BIDGOOD. 

